The present invention relates to a restarting device of a pump change-over valve for restarting an operation of a pump automatically in such an event that the operation of the pump is shut down due to the change-over valve stopping in a neutral position. The change-over valve is to be moved forth and back to switch the operation of the pump.
Among prior art pumps (for example, diaphragm-type pumps), a pump comprising a pair of diaphragms has been known. The respective diaphragms partition a pump main body into fluid delivering chambers and driving chambers, respectively.
Such diaphragm-type pump has employed a certain configuration, in which when a fluid-in-transfer in a first fluid delivering chamber located at a first diaphragm side is to be discharged, a driving fluid (e.g., a compressed air) is supplied to the first driving chamber located at the first diaphragm side to increase a volume of the first driving chamber. Therefore, the volume of the first fluid delivering chamber located at the first diaphragm side is decreased, while simultaneously the driving fluid in the second driving chamber located at the second diaphragm side is exhausted to decrease the volume thereof and, thus, to increase the volume of the second fluid delivering chamber located at the second diaphragm side. As a result, the second fluid delivering chamber sucks the fluid-in-transfer.
Further, in this configuration, when the fluid-in-transfer in the second fluid delivering chamber located at the second diaphragm side is to be discharged, the driving fluid is supplied to the second driving chamber located at the second diaphragm side to increase the volume of the second driving chamber. Therefore, the volume of the second fluid delivering chamber is decreased while simultaneously the driving fluid in the one driving chamber located in the first diaphragm side is exhausted to decrease the volume thereof and, thus, increase the volume of the first fluid delivering chamber located at the first diaphragm. As a result, the first fluid delivering chamber sucks the fluid-in-transfer.
Further, this kind of diaphragm-type pump is typically provided with a change-over valve, which is to be moved forth and back to switch an operation of the pump between a first mode for discharging the fluid-in-transfer in the first fluid delivering chamber and causing the second fluid delivering chamber to suck the fluid-in-transfer, and a second mode causing the first fluid delivering chamber to suck the fluid-in-transfer and for discharging the fluid-in-transfer in the second fluid delivering chamber.
However, because there is a neutral position in this change-over valve and, disadvantageously, stopping of a valve body in the neutral position may lead to shut down of the operation of the pump, a variety of improvement has been introduced into a pump design in order to solve this problem. Such improvements include, for example, a system, based on the fact that the pressure of the fluid-in-transfer drops when the change-over valve malfunctions, that detects the pressure drop and engages the reset button to restart the change-over valve. An alternative system detects the reciprocating motion of the valve body using a metal detecting sensor, and if there is no detection signal generated in a predetermined period, the system determines that the change-over valve has malfunctioned and engages the reset button to restart the change-over valve.
However, if the fluid-in-transfer is flammable and a care must be taken to avoid an explosion, the detection using the electric system is not suitable.
Additionally, it could be hardly said that a restarting device according to the prior art has a configuration enabling the reliable detection of the malfunctioning of the change-over valve to restart the pump.
The present invention has been made in view of the above problems, and an object thereof is to provide a restarting device of the pump change-over valve for restarting an operation of the pump automatically by using the driving fluid in such an event that the operation of the pump is shut down due to the change-over valve stopping in a neutral position. The change-over valve is to be moved forth and back to switch the operation of the pump.
According to the present invention, there is provided a restarting device of a pump change-over valve in a pump, in which the pump comprises a pump main body and a change-over valve. The pump main body is operated in such a manner that, when a fluid-in-transfer in a first fluid delivering chamber is to be discharged, a driving fluid is supplied to a first driving chamber to increase a volume of the first driving chamber and, thus, decrease a volume of the first fluid delivering chamber. Simultaneously, the driving fluid in a second driving chamber is exhausted to decrease a volume thereof and, thus, increase a volume of the other fluid delivering chamber. Thus the second fluid delivering chamber sucks the fluid-in-transfer. When the fluid-in-transfer in the second fluid delivering chamber is to be discharged, the driving fluid is supplied to the second driving chamber to increase the volume of the second driving chamber and, thus, decrease the volume of the second fluid delivering chamber. Simultaneously, the driving fluid in the first driving chamber is exhausted to decrease the volume thereof and, thus, increase the volume of the first fluid delivering chamber, thereby causing the first fluid delivering chamber to suck the fluid-in-transfer.
The change-over valve is operable to make a reciprocating motion to switch the operation of the pump main body between a first mode for discharging the fluid-in-transfer in the first fluid delivering chamber while causing the second fluid delivering chamber to suck the fluid-in-transfer, and a second mode causing the first fluid delivering chamber to suck the fluid-in-transfer while discharging the fluid-in-transfer in the second fluid delivering chamber.
The change-over valve is provided with a pair of pressure chambers formed in both ends on the back face sides of its valve body, respectively, into which the driving fluid is supplied to induce a pressure difference to switch the direction of movement of the valve body. The pump main body includes a balancing valve in which both end portions face the first driving chamber and the second driving chamber, respectively, If the change-over valve malfunctions and the pressures in both driving chambers become balanced, the balancing valve is to be held in an intermediate position, and is then to induce the pressure difference between the pair of pressure chambers.
According to another embodiment of the present invention there is provided a restarting device of a pump change-over valve in a pump, in which the pump comprises a pump main body and a change-over valve. The pump main body is provided with a pair of diaphragms for defining fluid delivering chambers and driving chambers. The pump main body is operated in such a manner that, when a fluid-in-transfer in a first fluid delivering chamber located at a first diaphragm side is to be discharged, a driving fluid is supplied to a first driving chamber located at the first diaphragm side to increase a volume of the first driving chamber and, thus, decrease a volume of the first fluid delivering chamber. Simultaneously, the driving fluid in the second driving chamber located at the second diaphragm side is exhausted to decrease a volume thereof and, thus, increase a volume of a second fluid delivering chamber located at the second diaphragm side, thereby causing the second fluid delivering chamber to suck the fluid-in-transfer. When the fluid-in-transfer in the second fluid delivering chamber is to be discharged, the driving fluid is supplied to the second driving chamber to increase the volume of the second driving chamber and, thus, decrease the volume of the second fluid delivering chamber. Simultaneously, the driving fluid in the first driving chamber is exhausted to decrease the volume thereof and, thus, increase the volume of the first fluid delivering chamber thereby causing the first fluid delivering chamber to suck the fluid-in-transfer.
The change-aver valve is operable to make a reciprocating motion to switch the operation of the pump main body between a first mode for discharging the fluid-in-transfer in the first fluid delivering chamber while causing the other fluid delivering chamber to suck the fluid-in-transfer, and a second mode causing the first fluid delivering chamber to suck the fluid-in-transfer while discharging the fluid-in-transfer in the second fluid delivering chamber.
The change-over valve is provided with a pair of pressure chambers formed in both ends on the back face sides of its valve body, respectively, into which the driving fluid is supplied to induce a pressure difference to switch the direction of movement of the valve body. The pump main body is provided with a balancing valve having both end portions facing the first driving chamber and the second driving chamber, respectively. If the change-over valve malfunctions and the pressures in both driving chambers are balanced, the balancing valve is to be held in an intermediate position and is then to induce the pressure difference between the pair of pressure chambers.
The pump main body may be further provided with a pilot valve for inducing a pressure difference between the pair of pressure chambers, and a direction of movement of the pilot valve is switched by the pair of diaphragms.
The pump main body may be further provided with an exhaust path for exhausting the driving fluid in the own driving chambers toward an outside. The balancing valve is further provided with a throttle valve for throttling said exhaust path when said balancing valve is positioned in a neutral position.